1. Field of the Invention
The present invention relates to an air valve having a cover that is carried by a pipe connector connected generally coaxially thereto such that the upper part of the pipe connector is surrounded by the wall of the cover, a first ring-shaped seat ridge carried by and sealingly connected to the cover wall, a second ring-shaped seat ridge generally coaxial with the cover wall and sealingly connected to the upper part of the pipe connector, and a valve plate vertically movable in the cover and carrying an annular, valve washer.
2. Description of the Related Art
Air valves are well known and can be fitted to the upper end of a waste pipe, or soil pipe, to which water closets, baths, wash basins, kitchen sinks, etc. can be connected via a so-called water seal. The air valve will normally close when the pressure in the pipe to which the valve is connected is the same as the pressure outside the pipe. The valve shall also seal the pipe channel effectively when the pressure in the pipe is higher than the ambient pressure. When the pressure in the pipe is lower than the ambient pressure, however, the valve will open and allow ambient air to enter so as to equalize the subpressure. This prevents the liquid in the water-seal being sucked away therefrom, which would then allow the waste gases to pass freely into the rooms and spaces in which the water-seal was installed. When fitted to a waste pipe, the air valve will also prevent odors and warm and moist air from flowing out from the upper end of the waste pipe, which enables installation of the sewerage system to be terminated indoors.
Valves of this particular kind will normally include a vertically movable valve plate which carries on its underside an annular sealing washer whose radially inner and outer edge-parts are able to rest sealingly onto concentrical, upwardly facing valve-seat rings, wherewith the washer seals the annular gap between said ring seats. The valve washer normally rests on the seats under the influence of the combined weight of the sealing washer and the guided plate carrying the washer. The valve can be made to open in response to relatively small pressure differences, by ensuring that it is light in weight. The valve is then also able to open very quickly, even after having been in a sealing mode for a relatively long period of time, particularly because the low contact force reduces the tendency of the washer to stick.
The sealing washer must be thin and essentially flat in order to ensure effective sealing abutment with the ring-shaped seats at a low abutment force.